Returning home from a three-week trek on foot to deliver free medical care to the remotest regions of the country, the aid workers — six Americans, a Briton, a German and four Afghans — had just finished eating when they were accosted by gunmen with long dyed-red beards, the police said.

The gunmen marched them into the forest, stood them in a line and shot 10 of them one by one.

...The Taliban claimed responsibility for the killings, accusing the group of being spies and Christian missionaries.

This blog and others have expressed concern about the erosion of humanitarian neutrality in Afghanistan, with one possible contributor the attempt to coordinate aid and the military.

There is no evidence that these particular killings were due to such factors; obviously the immediate responsibility is with the evil and hate-filled men who were the murderers. Our most sincere condolences to the families and friends of the victims.

UPDATE: Aug 9 4:15pm. On Twitter and on one comment on this blog, there has been criticism of my introducing the humanitarian neutrality issue in discussing this tragedy. If there was anyone personally offended by this, I apologize; I meant no disrespect to the victims of this horrible tragedy. Just as with other tragedies in aid, one wants both to offer condolences to the victims and to discuss ways to lessen the likelihood of future tragedies of the same kind. The second is obviously of no consolation to the victims.

I have many friends who are aid workers; my family and I sometimes informally act as aid workers ourselves. Discussing prevention of such tragedies is not a partisan debating point, it is very close to home. I believe the erosion of humanitarian neutrality is to be regretted and reversed, both on the grounds of principle and for the sake of protecting aid workers (including those who never moved away from neutrality).

When I said there was no evidence linking these murders to the erosion of humanitarian neutrality, I was making a generic statement that always applies -- we can never tell exactly what caused one particular horrific outcome.

However, there are still plenty of grounds to worry about new risks to aid workers if they are perceived as not neutral -- common sense, case study judgments, and the general trend that attacks on aid workers have increased at the same time as the erosion of humanitarian neutrality. I admit this is far from a rigorous demonstration, but on whom should be the burden of proof? On those who have moved away from the long-standing principle of humanitarian neutrality, or on those who want to preserve and defend it?